1. Field of the Invention
The present invention relates generally to the imaging of targets, e.g., trucks, pallets, trains, cars and the like. More particularly, the invention is directed to methods and systems for characterizing a target's cargo holding as empty or non-empty using imaging.
2. Background
There are many instances in the security or customs field when it is necessary to examine or inspect, in a non-destructive way, the contents of a target object, such as a closed package, box, suitcase, cargo container, automobile semi-trailer, tanker truck, railroad car, e.g., box car or tanker car, or the like. In other instances, it may be necessary to verify, in a non-destructive way, that the target object is empty as declared by the shipper and insure that there are no hidden compartments. For example, customs departments are routinely charged with the responsibility of inspecting vehicles coming into a country to make sure such vehicles do not contain drugs or other contraband, or leaving the country with stolen automobiles, drug money, and other illicit contraband. Similarly, drug smugglers frequently carry out their criminal acts by hiding illegal drugs in vehicles such as tanker trucks, and then sending the trucks through a border checkpoint. When security personnel encounter suspicious vehicles or other containers being transported over international boundaries, they must perform a careful time consuming (˜½ hour) inspection of such vehicles to ascertain their contents and/or verify that they are empty. Similarly, when suspicious trucks or cars enter compounds overseas having U.S. troops or containing embassy offices, they must be inspected for hidden vehicle bombs, poisonous gases, etc., even though they may have been declared as empty.
When suspicious vehicles are discovered, they generally must be examined or inspected on location in what is referred to as a “secondary inspection area.” If secondary inspection reveals the presence of contraband (e.g., drugs), then the vehicle may be impounded, the driver arrested, and the contraband disposed of. If, on the other hand, the examination reveals the absence of contraband or confirms that the vehicle is empty, then the vehicle may be allowed to proceed in the normal manner.